Characterization of a maize endosperm culture expressing zein genes and its use in transient transformation assays.

An endosperm derived tissue culture of maize (Zea mays L.) variety A636 has been characterised for its ability to synthesize zein protein and respond to a zein gene regulatory element. Western analysis with zein specific antibodies revealed the distinct presence of zein proteins of the 15, 19 and 21 kDa classes in this tissue, in contrast to an embryo-derived Black Mexican Sweet variety tissue culture which exhibited no zein proteins. Transient transformation studies with a cauliflower mosaic virus 35S promoter and luciferase reporter gene construct demonstrate that protoplasts from this tissue culture, but not from the embryo-derived culture, respond positively to the potential enhancer which is located approximately 300 base pairs upstream of the coding region in most zein genes of maize, thus establishing the usefulness of this culture for studies of tissue specific gene regulation.